How Do Progesterone Pills Work?

What is Progesterone?

Progesterone is a naturally occurring hormone that is secreted mainly by the corpus luteum (in the ovaries), but also by the adrenal glands in smaller amounts and in the placenta during pregnancy. Low progesterone may cause symptoms such as menstrual disorders, infertility or thyroid dysfunction amongst other symptoms.

What Progesterone Does

When functioning properly, the secretion of progesterone thickens the endometrial lining, allowing the implantation of an egg. If the egg does not become fertilized, the production ceases and the lining is shed, along with the unfertilized egg. Because of this process, women who have low progesterone become pregnant and miscarry, or may experience difficulty with implantation occurring altogether.

How Progesterone Pills Work

Progesterone treatment pills are used to normalize low levels and can be natural or synthetic. A healthy environment is created within the womb by increasing low progesterone levels to normal range. Blood vessel development is increased, and a thicker lining is formed. This is beneficial in regulating abnormal menstrual cycles.

Progesterone in Contraception

In most birth control pills, progesterone is paired with estrogen and taken orally. When progesterone serum levels are high, the environment within the womb is no longer supportive of implantation, therefore pregnancy is prevented. During one week of the menstrual cycle, a placebo pill may be taken, allowing progesterone levels to drop. The thick lining is shed and menstruation occurs.

Hormone Replacement Therapy

Progesterone normally has a natural balance with estrogen during a woman's pre-menopausal years. During a woman's peri-menopausal stage, this balance is disrupted when progesterone levels decline. This imbalance may create symptoms such as low libido, foggy thinking, breast tenderness and depression. These menopausal symptoms can be treated by supplementing the system with progesterone to restore that balance.